On the fatigue properties of a third generation aluminium-steel butt weld made by Hybrid Metal Extrusion & Bonding (HYB)

•Al-steel HYB butt joint exhibits unique fatigue properties in as-welded condition.•Interfacial cracking is prevented by a high intrinsic Al-Fe bond strength.•Fatigue crack development occurs at the weld toe on the Al side of the joint.•Joint fatigue strength is comparable with that of corresponding Al-Al weldments.